The present invention relates to a system for carbonating and cooling liquid for the production of beverages such as soft drinks. In conventional carbonating systems, gaseous carbon dioxide is directed into the top of a carbonator cooling tank which includes refrigerated cooling plates. The product enters the top of the tank and flows downwardly over the cooling plates. If liquid carbon dioxide is directed into a conventional carbonator cooler of the foregoing type, excessive ice crystals would form and freeze to the product line internal surfaces. One reason for such freezing is the excessive refrigeration generated from injection pressure without provision for effective heat exchanger of the same.
The use of liquid carbon dioxide for carbonation of liquids provides the major advantage of cooling the liquid simultaneously with carbonation. It is well known that the reduction of temperature renders the carbonated liquids susceptible to increased amounts of carbon dioxide to form a stable product. Once stabilized, the product tends to retain the carbon dioxide even at increased temperatures. One system for carbonating liquid which employs an auxiliary liquid carbon dioxide injection is set forth in my U.S. Pat. No. 3,832,474. There, carbon dioxide is injected from a liquid carbon dioxide valve from a high pressure metering pump into a line connected to the bottom of a stabilizing tank. Liquid carbon dioxide expands into a gaseous state and simultaneously produces a refrigeration or cooling effect. In the above system, carbonated liquid is withdrawn in a stream from the bottom of the tank.
If the above system were employed in a highly carbonated product with the total carbon dioxide being supplied in liquid form, ice crystals would tend to form in the product and float to the top of the liquid in the tank. Since there is no disclosure of a technique for melting such crystals, they could accumulate and form a layer of sufficient depth to disrupt the uniformity of carbonation. Another disadvantage of the system is that it does not optimize the massive refrigeration generated at the point of introduction of the carbon dioxide into the stabilizing tank. The excess refrigeration at this point could be employed more effectively for energy conservation.